28-07-2014, 11:04 AM
Explosive Forming
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Background:
All processes, after sufficient time, are visited by a new generation of workers that
contemplates process merits and demerits for specific applications. The process that is
presently being revisited by academics and industry together is explosive forming. For over 100
years, it has been recognized that explosives can be used in a controlled way in the
manufacture of profiled metal components. The required profile results from the explosive
force that directly or indirectly deforms the metal. Explosive forming is a broad term covering
many process variations. Early patents relating to explosive forming appeared at the end of the
19th and at the beginning of the 20th century. An increasing number of economically successful
applications were being seen in the early 1970s, with the manufacture of large aluminum and
high strength steel parts.
Explosive forming was used in the 1960s for aerospace applications, such as the chine plates of
the SR-71 reconnaissance plane and various Soviet rocket parts; it continued to be developed in
Russia, and the organizing committees of such events as EPNM tend to contain many members
from the former Soviet Union. It proved particularly useful for making high-strength corrugated
parts which would otherwise have to be milled out of ingots much larger than the finished
product. An example would be a yacht constructor who produced boat hulls by making a
concrete "swimming pool" into which sheet-metal was placed, and when water filled and
explosively fired, produced a complete hull-form
Introduction:
Explosive forming is a metalworking technique in which an explosive charge is used instead of a
punch or press. Metal parts are shaped in dies by using an explosive charge to generate forming
pressure. The explosives used are generally high explosive chemicals, gaseous mixtures, or
propellants. Explosives can deliver a huge amount of power. Although most explosive
detonations are destructive, the power from an explosive charge can be used to manufacture
parts. By using the high explosive forming, items can be obtained, with different shapes and
almost unlimited overall size, made of heavy-duty materials. During the course of development
of new forming methods a number of high energy- rate techniques have been categorized as
explosive forming. These methods have included the use of chemical low and high explosives
pneumatic systems, electrical discharge systems, and magnetic devices.
Advantages:
1. It can simulate a variety of other conventional metal forming techniques such as stamp
or press forming and spin forming in a single operation.
2. Explosive hydro forming can efficiently form large parts up to 4’ square or 10’ in
diameter.
3. It is particularly suitable for short production runs of a large part such as occurs in
aerospace applications.
4. Maintains precise tolerances.
5. Eliminates costly welds.
6. Controls smoothness of contours.
7. Reduces tooling costs.
8. Less expensive alternative to super-plastic forming.
Limitations:
1. Low tooling costs, but high labor cost.
2. Suitable for low quantity production.
3. Due to shock waves and spillage of water it is not suitable to carry out indoor.
4. It should be done in open air.